JP4492292B2 - Induction hardening method and hardening jig - Google Patents

Description

  The present invention relates to a measure for improving dimensional accuracy when induction-quenching a ring-shaped steel member.

A steel member having a ring shape such as a gear part having a tooth shape on an outer peripheral surface is widely used as a part of various mechanical devices. For example, in an automatic transmission of an automobile, a diff ring gear, a counter gear, and many other ring-shaped parts are used.
Since these ring-shaped steel members are usually required to have high strength characteristics, the outer peripheral surface may be subjected to induction hardening as a countermeasure.

  By the way, induction hardening is very excellent as a measure for improving the strength, but may reduce the dimensional accuracy. For example, the roundness may be lower after induction hardening than before the treatment. There is no problem even if a conventional induction hardening method is adopted as long as the reduction in roundness does not lead to a decrease in performance. However, when the reduction in roundness leads to a reduction in the performance of the component, it is necessary to add a correction process for improving the roundness after induction hardening.

For this reason, development of a method capable of suppressing a decrease in roundness in induction hardening is desired, but a sufficient solution has not yet been produced.
For example, Patent Document 1 discloses a jig used for improving the cylindricity when induction-hardening a cylindrical member on its inner peripheral surface. However, the jig shown here cannot improve the roundness when induction hardening is performed on the outer peripheral surface.

Japanese Patent Laid-Open No. 11-131133

  The present invention has been made in view of such conventional problems, and is intended to provide a high-frequency quenching method and a jig used therefor that can suppress a decrease in roundness of a ring-shaped steel member. is there.

1st invention is the method of performing induction hardening to the outer peripheral surface of the said outer peripheral ring part in the steel member which has a substantially cylindrical outer peripheral ring part,
A substrate having a flat reference surface, and a protrusion provided so as to protrude from the reference surface at a central portion of the substrate, the cross-sectional shape of the protrusion being a perfect circle and Using a pressing member provided with a pressing surface composed of a tapered surface inclined so that the outer diameter becomes smaller as approaching the tip on the outer periphery,
At least a part of the pressing surface is provided on the inner peripheral side of the outer peripheral ring portion from the at least one axial end surface side of the outer peripheral ring portion with a gap provided between the axial end surface and the reference surface. Press the pressing member to make contact,
In a state where the pressing member is applied with a biasing force by a biasing means in a direction relatively approaching the steel member, the outer peripheral surface of the outer peripheral ring portion is subjected to induction hardening treatment,
During the induction hardening process, the outer ring part is heated by induction heating to thermally expand the outer ring part while exerting a force on the outer ring part from the pressing surface by the biasing force. The pressing member is relatively advanced until the reference surface comes into contact with the axial end surface, and then the induction heating is terminated and the outer peripheral ring portion is rapidly cooled to contract the outer peripheral ring portion. there from the pressing surface to induction hardening method characterized that you apply force to improve the roundness in the inner peripheral side of the outer ring portion (claim 1).

  In the induction hardening method of the present invention, a quenching jig including a pressing member having a special structure having the pressing surface and the reference surface is used. And while making the said press surface contact the inner peripheral side of the said outer periphery ring part, the clearance gap is provided between the said reference surface and the axial direction end surface of an outer periphery ring part, and a press member approaches a steel member. The induction hardening is performed with a biasing force applied in the direction.

  In the induction hardening process, first, the outer peripheral surface of the outer ring portion is heated by induction heating, so that the outer ring portion is thermally expanded. Therefore, the inner peripheral side of the outer peripheral ring portion tends to be separated from the pressing surface. Here, since the urging force is applied to the pressing member in the direction approaching the steel member as described above, a force acts on the pressing member in a relatively forward direction. Due to this relative forward force, at the initial stage where the degree of thermal expansion of the outer peripheral ring portion is at least small, the contact state between the pressing surface and the inner peripheral side of the outer peripheral ring portion is maintained, and from the pressing surface to the outer peripheral ring portion. A force acts to increase the roundness on the inner circumference side. Thereby, the effect of maintaining the roundness during heating can be obtained.

  As the outer ring portion expands due to heating, the pressing member relatively moves forward. However, when the reference surface around the pressing surface comes into contact with the end surface of the outer ring portion, the relative advance is restricted. When the outer peripheral ring portion further expands at this point, the inner peripheral side and the pressing surface are separated from each other. Of course, at this time, the dimensional relationship between the two may be adjusted and the contact relationship may be maintained.

  Next, in the induction hardening process, rapid cooling such as water cooling is performed. At this time, the outer peripheral ring portion contracts due to cooling. As a result, the pressing surface of the pressing member and the inner peripheral side of the outer ring portion are not only when the contact state between the two is maintained during heating, but also when the contact state is released. The contact state is restored and both are strongly pressed. That is, at the time of contraction due to cooling, the inner peripheral side of the outer peripheral ring portion is strongly pressed against the pressing surface, and the roundness reduction is suppressed.

As described above, in the induction hardening method of the present invention, by using a quenching jig including a pressing member having a special structure having the pressing surface and the reference surface, the trueness of the ring-shaped steel member is obtained. The induction hardening process to the outer peripheral surface can be performed while suppressing a decrease in circularity.
The reference surface of the pressing member is preferably provided on the entire outer circumference side of the protruding portion provided with the pressing surface, but may of course be provided partially rather than the entire circumference.

Next, the second invention is a quenching jig to be mounted on the steel member when induction hardening is performed on the outer peripheral surface of the outer peripheral ring portion in a steel member having a substantially cylindrical outer peripheral ring portion. ,
A substrate having a flat reference surface, and a protrusion provided so as to protrude from the reference surface at a central portion of the substrate, the cross-sectional shape of the protrusion being a perfect circle and A pressing surface comprising a tapered surface inclined so that the outer diameter decreases toward the outer periphery toward the outer periphery, and a gap is formed between the axial end surface and the reference surface from at least one axial end surface side of the outer peripheral ring portion. A pressing member configured such that at least a part of the pressing surface can come into contact with the inner peripheral side of the outer peripheral ring portion ,
Biasing means for applying a biasing force in a direction in which the pressing member approaches the steel member relatively,
When the pressing member is subjected to induction hardening in the outer peripheral surface of the outer peripheral ring portion in a state in which a biasing force is applied in a direction relatively approaching the steel member,
During the induction hardening process, while applying force from the pressing surface to the outer ring part by the biasing force, the outer ring part is heated by induction heating to thermally expand the outer ring part. The pressure member is relatively advanced until the surface comes into contact with the axial end surface, and then the induction heating is terminated and the outer ring portion is rapidly cooled to contract the outer ring portion. The quenching jig is configured to be able to apply a force for improving the roundness from the pressing surface to the inner peripheral side of the outer peripheral ring portion (Claim 7).

  The quenching jig of the present invention has a pressing member having a special structure including the reference surface and the pressing surface. Therefore, by using this, as described above, an excellent induction hardening method can be realized.

In the first invention, as the hardening jig, the first pressing member which is the pressing member to be contacted from one axial end surface side of the outer peripheral ring portion, and the other axial end surface side is contacted The second pressing member, which is the pressing member to be used, sandwiches the steel member thereby, and the pressing surface of the first pressing member and the pressing surface of the second pressing member face each other. The high-frequency quenching process is performed in a state in which the first pressing member and the second pressing member are brought into contact with the inner peripheral side of the outer peripheral ring portion and a biasing force is applied to the first pressing member and the second pressing member in a direction in which the distance between both is reduced. It is preferable to apply ( Claim 3 ).

  In this case, induction hardening is performed in a state where the steel member is sandwiched between the first pressing member and the second pressing member. Thereby, the roundness improvement of the said outer periphery ring part which the press surface of said two press members each faces can be aimed at. That is, the roundness improvement effect can be obtained from both ends of the outer peripheral ring portion. For this reason, it is possible to suppress a taper defect in which the diameter varies in the axial direction.

Further, the pressing surface of the pressing member is a tapered surface that is inclined so that the outer diameter becomes smaller as it approaches the tip . In this case, the contact state between the pressing surface and the inner peripheral side of the outer peripheral ring portion can be easily realized.
In this case, it is preferable that the pressing surface of the pressing member is in contact with the apex angle portion between the axial end surface and the inner peripheral surface of the outer peripheral ring portion. Thereby, the contact state with the press surface which consists of the said taper surface, and the inner peripheral side of the said outer periphery ring part can be implement | achieved still more easily.

  Further, as the pressing member, a member having a truncated cone shape or a columnar shape in which the tip end surface of the projecting portion is flat is used, and a tip corner portion connected to the tip end surface in the pressing surface is used as the outer peripheral ring portion. It can also be made to contact | abut to the internal peripheral surface in (Claim 5).

  Further, the steel member is preferably a ring gear formed by forming a tooth profile on the outer peripheral surface of the outer peripheral ring portion. For example, a ring gear typified by a diff ring gear used in an automatic transmission of an automobile needs to have a high hardness on the tooth profile surface formed on the outer peripheral surface and is required to have high roundness. Therefore, it is very effective to adopt the induction hardening method of the present invention.

In the second invention, the quenching jig is in contact with the first pressing member which is the pressing member to be contacted from one axial end face side of the outer peripheral ring portion, and from the other axial end face side. A second pressing member that is the pressing member to be sandwiched, thereby sandwiching the steel member, and the pressing surface of the first pressing member and the pressing surface of the second pressing member face each other. It is preferable that the outer peripheral ring portion is configured to be able to contact the inner peripheral side ( Claim 9 ). According to this quenching jig, as described above, high-frequency quenching can be performed in a state where the steel member is sandwiched between the two pressing members, and the effect of suppressing the reduction in roundness and the effect of suppressing the taper defect can be obtained. Can do.

Further, the pressing surface of the pressing member is a tapered surface that is inclined so that the outer diameter becomes smaller as it approaches the tip . In this case, the presence of the tapered surface makes it possible to easily realize a contact relationship with the inner peripheral side of the outer peripheral ring portion.
The protruding portion provided with the pressing surface can have a truncated cone shape or a columnar shape, but the pressing surface formed of the tapered surface can be provided by forming the truncated cone shape.

  Moreover, as a steel member to which the first and second inventions can be applied, a part constituted only by the part of the outer ring part, a part provided with an inner ring part thinner than this inside the outer ring part, The inner ring portion is located in the vicinity of the center portion of the inner peripheral surface of the outer ring portion, and the apex angle portion is present on both end surface sides of the outer ring portion, or the inner ring portion is one of the outer ring portions. There are various shapes such as one that is connected to the end surface side and the apex angle portion is not present only on the opposite surface.

Example 1
An induction hardening method and a hardening jig according to an embodiment of the present invention will be described with reference to FIGS.
In this example, as shown in FIG. 7, induction hardening is performed on the outer peripheral surface 810 of the outer peripheral ring portion 81 in the steel member 8 having the outer peripheral ring portion 81 having a substantially cylindrical shape. Specifically, the steel member 8 is a diff ring gear which is a part for an automatic transmission (A / T) of an automobile, and forms a tooth profile having a large number of teeth 811 on the outer peripheral surface 810 of the outer peripheral ring portion 81. Do it. Further, an inner ring portion 83 having an axial dimension (thickness) smaller than that of the outer ring portion 81 is formed on the inner periphery side of the outer ring portion 81. The inner ring portion 83 extends from the central portion of the inner peripheral surface 816 of the outer peripheral ring portion 81, and the inner peripheral surface 816 exists on both sides thereof. Further, apex angle portions 821 and 822 exist between the axial end surfaces 801 and 802 of the outer peripheral ring portion 81 and the inner peripheral surface 816. In addition, as shown in FIG. 4 and the like which will be described later, the apex angle portions 821 and 822 have two corner portions by chamfering, and one of them functions as the apex angle portion in the present invention.

Moreover, the hardening jig 1 used in this example includes two pressing members (a first pressing member 10 and a second pressing member 2) as shown in FIG. The first pressing member 10 and the second pressing member 2 both protrude from the reference surfaces 12 and 22 at the central portions of the substrates 12 and 22 having the flat reference surfaces 15 and 25 and the substrates 12 and 22. It has the protrusion parts 13 and 23 provided in this way. The protrusions 13 and 23 have a circular shape in cross section and are provided with pressing surfaces 11 and 21 on the outer periphery thereof. Moreover, the protrusion parts 13 and 23 of this example are taper surfaces inclined so that an outer diameter becomes small as the said press surfaces 11 and 21 approach a front-end | tip, and are exhibiting the truncated cone shape which equipped this with the side surface. Further, the first pressing member 11 is provided with a back side protruding portion 19 for restricting the position of the spring 4 to be described later on the side opposite to the surface on which the protruding portion 13 is provided.

When the induction hardening process is performed on the steel member 8 using the quenching jig 1 having the pressing members 10 and 2 having the above-described configuration, first, as shown in FIG. From the surface side, the first pressing member 10 and the second pressing member 2 are pressed against each other.
Then, as shown in FIG. 2, the tapered surface 11 of the first pressing member 10 is brought into contact with the apex angle portion 821 between one axial end surface 801 of the outer peripheral ring portion 81 and the inner peripheral surface 816. Further, the tapered surface 21 of the second pressing member 2 is brought into contact with the apex angle portion 822 between the other axial end surface 802 of the outer peripheral ring portion 81 and the inner peripheral surface 816.
At this time, the reference surfaces 15 and 25 of the first pressing member 10 and the second pressing member 2 are both maintained in a state of being separated from the axial end surfaces 801 and 802 of the outer peripheral ring portion 81.

  The urging plate 3 is disposed on the back side of the first pressing member 10 via a spring 4. The spring 4 is disposed on the outer peripheral side of the back side protrusion 19 of the first pressing member 10 and the protrusion 39 of the urging plate 3. Then, as shown in FIG. 3, these are sequentially arranged from the second pressing member 2 on the mounting table 71 of the induction hardening apparatus, and by a predetermined pressure by the biasing shaft 72 connected to the biasing plate 3. The urging plate 3 is fixed while pressed downward.

In this state, the outer peripheral surface 810 is induction-heated by energizing the coil 75 arranged to face the outer peripheral surface 810 of the outer peripheral ring portion 81.
Since the outer peripheral ring portion 81 gradually expands due to the induction heating, as shown in FIG. 4, the contact position between the tapered surface 11 of the first pressing member 10 and the apex angle portion 821 is as shown in FIG. The state changes from the state to the state shown in FIG. 5B, and the reference surface 15 moves forward to approach the steel member 8 to a position where it comes into contact with the axial end surface 801 of the outer peripheral ring portion 81. The contact state between the second pressing member 2 and the apex angle portion 822 is similarly changed (not shown).

  Furthermore, when the thermal expansion of the outer peripheral ring portion 81 proceeds, as shown in FIG. 4C, the contact state between the apex angle portion 821 on the inner peripheral side and the pressing surface 12 of the first pressing member 10 is released. A gap is created between them. The contact state between the second pressing member 2 and the apex angle portion 822 is similarly changed (not shown). Note that the roundness of the outer peripheral ring portion 81 is maintained by the force exerted from the pressing surface 12 until it is separated from the pressing surface 12.

Next, as shown in FIG. 5, when the heating of the outer peripheral surface 810 of the outer peripheral ring portion 81 is completed, the cooling water 77 is ejected from the coil 75 and the outer peripheral ring portion 81 is rapidly cooled from the outer peripheral surface 810. As a result, as shown in FIG. 4D and FIG. 6, the outer peripheral ring portion 81 contracts due to cooling, and the pressing surface 11 of the first pressing member 10 and the apex angle portion 811 on the inner peripheral side of the outer peripheral ring portion 81 again. And the contact state between the pressing surface 21 of the second pressing member 2 and the apex angle portion 821 on the inner peripheral side of the outer peripheral ring portion 81 are restored. And the force which improves roundness from the press surfaces 11 and 21 to the inner peripheral side of the outer periphery ring part 81 is provided.
Thereafter, by removing the steel member 8 from the quenching jig 1, a series of induction hardening processes for the steel member 8 is completed.

  Thus, in the induction hardening method of the present example, the quenching treatment having the first pressing member 10 and the second pressing member 2 having a special structure including the tapered surfaces 11 and 21 and the reference surfaces 15 and 25 described above. Tool 1 is used. The tapered surfaces 11 and 21 are brought into contact with the apex angle portions 821 and 822 in a state where a gap is provided between the axial end surfaces 801 and 802 of the outer peripheral ring portion 81 and the reference surfaces 15 and 25. Then, the induction hardening is performed in a state in which the pressing members 11 and 2 apply a biasing force in a direction approaching the steel member 8. Therefore, the contact state between the tapered surfaces 11 and 21 and the apex angle portions 821 and 822 is maintained during heating and cooling, and the roundness of the outer peripheral ring portion 81 can be prevented from being lowered.

  As described above, in the induction hardening method of this example, by using the quenching jig 1 having the pressing members 10 and 2 having a special structure including the reference surfaces 15 and 25 and the tapered surfaces 11 and 21. And the induction hardening process to the outer peripheral surface 810 can be performed, suppressing the roundness fall of the said ring-shaped steel member 8. FIG.

(Example 2)
In this example, as shown in FIGS. 8A to 8D, the tip corner 119 of the pressing surface 11 of the first pressing member 10 and the inner periphery of the outer ring portion 81 in the set stage before the induction hardening process. This is an example using the first pressing member 10 configured to contact the peripheral surface 816 and a second quenching member (not shown) configured similarly.
In this case, the pressing surfaces 11 and 21 of the first and second pressing members 10 and 2 and the contact position on the inner peripheral side of the outer peripheral ring portion 81 are only different from those in the first embodiment. The same effect can be obtained.

(Example 3)
In this example, as shown in FIGS. 9A to 9D, the pressing surface 11 of the first pressing member 10 and the inner peripheral surface 816 of the outer peripheral ring portion 81 are in the set stage before the induction hardening process. It is an example using the 1st press member 10 comprised so that a surface may contact | abut, and the 2nd quenching member (illustration omitted) comprised similarly.
Also in this case, the pressing surfaces 11 and 21 of the first and second pressing members 10 and 2 and the contact position on the inner peripheral side of the outer peripheral ring portion 81 are only different from those in the first embodiment. The same effect can be obtained.

Example 4
In this example, in order to quantitatively judge the excellent effect of Example 1, the roundness is evaluated by measuring the amount of ellipse after quenching together with the samples as other examples and comparative examples. It was. All the samples prepared as samples were obtained by quenching a steel member having the same shape as in Example 1.
Sample No. As E1, what was induction-hardened by Example 1 was used. That is, this is an example in which the apex portions 821 and 822 are pressed against the front and back objects by the tapered surfaces 11 and 21 of the first pressing member 10 and the second pressing member 2.

  Sample No. As shown in FIG. 10, E2 is obtained by changing the configuration of the quenching jig and performing the induction hardening process similar to that in Example 1. As the quenching jig, the first pressing member 10 to be brought into contact with one axial end face 801 side is the same as that of the first embodiment, and the member to be brought into contact with the other axial end face 802 is as follows. A member 91 in which the tapered surface 911 does not contact the apex portion 822 at all is used. That is, this is an example in which the contact state is asymmetric on the front and back sides.

  Sample No. As shown in FIG. 11, C1 is obtained by changing the configuration of the quenching jig and performing the same induction hardening process as in Example 1. The quenching jig is configured such that the tapered surfaces 921 and 931 do not contact the apex portions 821 and 822 at all in both the members 92 and 93 that are brought into contact with both axial end surfaces 801 and 802. In other words, this is an example in which the apex angle portions 821 and 822 of the outer peripheral ring portion 81 are in a free state where they are not restrained.

  Sample No. As shown in FIG. 12, C2 is obtained by performing a carburizing and quenching process in which rapid quenching is performed after the carburizing process, instead of induction quenching. As the quenching jig, a steel member 8 provided with a cradle 941 for arranging the steel member 8 so that its axial direction is in the horizontal direction and supporting the inner peripheral surface 836 of the inner ring portion 83 was used.

And as an evaluation of the roundness of each sample, the diameter was measured at a plurality of positions in the radial direction at three locations in the thickness direction (upper, middle, lower) from the outer peripheral surface 810 of the outer peripheral ring portion 81, and the maximum The difference between the diameter and the minimum diameter was calculated as the amount of ellipse (μm).
Moreover, the average value of the diameter in two places of an axial direction upper position and a lower position was calculated | required, and those difference (micrometer) was computed as taper amount.
These results are shown in FIG. In the same figure, the ellipse amount measurement result is shown as a bar graph for each measurement position, the ellipse amount value and the evaluation result are shown in the lower part, and the taper amount value and the evaluation result are shown in the lower part.

As can be seen from FIG. E1 shows that the amount of ellipse is small at any measurement position and has a very good roundness. It can also be seen that the taper amount is very small and the variation in the diameter in the axial direction is very small.
Sample No. E2 is a sample No. described later. It can be seen that the amount of ellipse is small compared to C1 and C2, and the roundness is sufficiently high. On the other hand, the taper amount was relatively large, and the variation in the diameter in the axial direction was large. Such a result is considered to be due to processing under asymmetric pressing conditions as described above. In addition, from this result, in the case where there is no problem as long as the roundness is good, this sample No. It can be seen that the processing condition E2 is sufficient.
On the other hand, Sample No. C1 and C2 have a small amount of taper and little variation in the diameter in the axial direction. The result was lower than E1 and E2.

Explanatory drawing which shows the procedure in which the hardening jig | tool in Example 1 is set to a steel member. Explanatory drawing which shows the state which set the jig | tool for hardening in Example 1 to the steel member. Explanatory drawing which shows the state which is carrying out induction heating of the outer peripheral surface of the outer peripheral ring part of the steel member in Example 1. FIG. In Example 1, (a) Explanatory drawing which shows the state before an outer periphery ring part thermally expands, (b) The outer peripheral ring part is in the middle of thermal expansion, Comprising: A reference surface is an axial end surface of an outer periphery ring part Explanatory drawing which shows the state immediately after contact | abutting, (c) Explanatory drawing which shows the state which the thermal expansion of the outer periphery ring part completed, and the press surface and the inner peripheral side of the outer peripheral ring part separated, (d) Outer ring part Explanatory drawing which shows the state after cooling. Explanatory drawing which shows the state which water-cools the outer peripheral surface of the outer peripheral ring part of the steel member in Example 1. FIG. Explanatory drawing which shows the state after the outer periphery ring part in Example 1 thermally expanded. The shape of the steel member in Example 1 is shown, (a) Top view, (b) AA arrow directional cross-sectional view. In Example 2, (a) Explanatory drawing which shows the state before an outer periphery ring part thermally expands, (b) The outer peripheral ring part is in the middle of thermal expansion, Comprising: A reference surface is an axial end surface of an outer periphery ring part Explanatory drawing which shows the state immediately after contact | abutting, (c) Explanatory drawing which shows the state which the thermal expansion of the outer periphery ring part completed, and the press surface and the inner peripheral side of the outer peripheral ring part separated, (d) Outer ring part Explanatory drawing which shows the state after cooling. In Example 3, (a) Explanatory drawing which shows the state before an outer periphery ring part thermally expands, (b) The outer peripheral ring part is in the middle of thermal expansion, Comprising: A reference surface is an axial end surface of an outer periphery ring part Explanatory drawing which shows the state immediately after contact | abutting, (c) Explanatory drawing which shows the state which the thermal expansion of the outer periphery ring part completed, and the press surface and the inner peripheral side of the outer peripheral ring part separated, (d) Outer ring part Explanatory drawing which shows the state after cooling. In Example 4, Sample No. Explanatory drawing which shows the set state of the jig for hardening at the time of processing E2. In Example 4, Sample No. Explanatory drawing which shows the setting state of the jig for hardening at the time of processing C1. In Example 4, Sample No. Explanatory drawing which shows the setting state of the jig for hardening at the time of processing C2. Explanatory drawing which shows the evaluation result in Example 4. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hardening jig | tool 10 1st press member 11 Tapered surface 2 2nd press member 21 Tapered surface 8 Steel member 81 Outer peripheral ring part 810 Outer peripheral surface 801, 802 Axial end surface 816 Inner peripheral surface 821, 822 Vertex angle part 83 Inner ring Part

Claims (9)

A method of performing induction hardening on the outer peripheral surface of the outer ring portion in a steel member having a substantially cylindrical outer ring portion,
A substrate having a flat reference surface, and a protrusion provided so as to protrude from the reference surface at a central portion of the substrate, the cross-sectional shape of the protrusion being a perfect circle and Using a pressing member provided with a pressing surface composed of a tapered surface inclined so that the outer diameter becomes smaller as approaching the tip on the outer periphery,
At least a part of the pressing surface is provided on the inner peripheral side of the outer peripheral ring portion from the at least one axial end surface side of the outer peripheral ring portion with a gap provided between the axial end surface and the reference surface. Press the pressing member to make contact,
In a state where the pressing member is applied with a biasing force by a biasing means in a direction relatively approaching the steel member, the outer peripheral surface of the outer peripheral ring portion is subjected to induction hardening treatment,
During the induction hardening process, the outer ring part is heated by induction heating to thermally expand the outer ring part while exerting a force on the outer ring part from the pressing surface by the biasing force. The pressing member is relatively advanced until the reference surface comes into contact with the axial end surface, and then the induction heating is terminated and the outer peripheral ring portion is rapidly cooled to contract the outer peripheral ring portion. induction hardening method for from the pressing surface, characterized that you apply force to improve the roundness in the inner peripheral side of the outer ring portion.   2. The induction hardening method according to claim 1, wherein the biasing means comprises a spring.   The second pressing member according to claim 1 or 2, wherein the first pressing member that is the pressing member that is contacted from one axial end surface side of the outer peripheral ring portion, and the second pressing member that is contacted from the other axial end surface side. The pressing member is used to sandwich the steel member, and the pressing surface of the first pressing member and the pressing surface of the second pressing member are arranged on the inner peripheral side of the outer peripheral ring portion that faces each other. The induction hardening process is performed, wherein the induction hardening process is performed in a state where an urging force is applied to the first pressing member and the second pressing member in a direction in which an interval between the first pressing member and the second pressing member is reduced. How to put. The high frequency according to any one of claims 1 to 3, wherein the pressing surface of the pressing member is brought into contact with an apex portion between an axial end surface and an inner peripheral surface of the outer peripheral ring portion. Hardening method.   The press member according to any one of claims 1 to 3, wherein the pressing member has a truncated cone shape or a columnar shape with a flat tip surface of the protruding portion, A high-frequency quenching method, wherein a leading end corner portion is brought into contact with an inner peripheral surface of the outer peripheral ring portion.   The induction hardening method according to any one of claims 1 to 5, wherein the steel member is a ring gear formed by forming a tooth profile on an outer peripheral surface of the outer peripheral ring portion. A quenching jig to be mounted on the steel member when induction hardening is performed on the outer peripheral surface of the outer ring portion in the steel member having a substantially cylindrical outer ring portion,
A substrate having a flat reference surface, and a protrusion provided so as to protrude from the reference surface at a central portion of the substrate, the cross-sectional shape of the protrusion being a perfect circle and A pressing surface comprising a tapered surface inclined so that the outer diameter decreases toward the outer periphery toward the outer periphery, and a gap is formed between the axial end surface and the reference surface from at least one axial end surface side of the outer peripheral ring portion. A pressing member configured such that at least a part of the pressing surface can come into contact with the inner peripheral side of the outer peripheral ring portion ,
Biasing means for applying a biasing force in a direction in which the pressing member approaches the steel member relatively,
When the pressing member is subjected to induction hardening in the outer peripheral surface of the outer peripheral ring portion in a state in which a biasing force is applied in a direction relatively approaching the steel member,
During the induction hardening process, while applying force from the pressing surface to the outer ring part by the biasing force, the outer ring part is heated by induction heating to thermally expand the outer ring part. The pressure member is relatively advanced until the surface comes into contact with the axial end surface, and then the induction heating is terminated and the outer ring portion is rapidly cooled to contract the outer ring portion. A quenching jig configured to be able to apply a force for improving roundness from the pressing surface to an inner peripheral side of the outer peripheral ring portion .   8. A quenching jig according to claim 7, wherein the biasing means comprises a spring.   9. The hardening tool according to claim 7, wherein the quenching jig is in contact with the first pressing member that is the pressing member to be contacted from one axial end surface side of the outer peripheral ring portion and the other axial end surface side. A second pressing member that is the pressing member to be sandwiched, thereby sandwiching the steel member, and the pressing surface of the first pressing member and the pressing surface of the second pressing member face each other. A quenching jig configured to be able to contact the inner peripheral side of the outer peripheral ring portion.

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